Theft Detection Lock uses AI, your device’s motion sensors, Wi-Fi, and Bluetooth to detect if someone unexpectedly takes your device and runs away. If Theft Detection Lock detects your device is taken from you, it automatically locks your device’s screen to protect its content. For example, if someone grabs the phone out of your hand and they run, bike, or drive away, the Theft Detection Lock may activate.

support.google.com/android/answer/15146908

I presume it waits for an abrupt spike in the accelerometer followed by going out of range of nearby Wi-Fi networks and Bluetooth connections. I am curious how well it works, and how often false positives occur.

I am also disappointed that it seems GrapheneOS does not offer a similar feature.